Apparatus and Methods for Repairing Aneurysms

ABSTRACT

An apparatus for repairing an aneurysm comprises a device having an inner graft tube and an inflatable outer balloon attached to an outer surface of the inner graft tube, and an inflatable deployment balloon. The inner graft tube is expandable within an artery to form a seal with the arterial wall above and/or below an aneurysm. The outer balloon is inflatable within the aneurysm with a rapidly settable substance to fill the aneurysm and support the device. The deployment balloon has an uninflated condition to fit within the inner graft tube and is inflatable within the inner graft tube to expand the inner graft tube within the artery and to maintain the inner graft tube expanded within the artery during inflation of the outer balloon.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation of prior U.S. patent application Ser.No. 10/481,386 filed Dec. 19, 2003, which claims priority fromInternational Application No. PCT/GB02/02750 filed Jun. 17, 2002 andfrom Great Britain patent application No. 0114918.6 filed Jun. 19, 2001,the entire disclosures of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention concerns devices for use in repairing aneurysms,especially of the abdominal aorta.

2. Brief Discussion of the Related Art

An aneurysm occurs when an arterial wall becomes weakened to the extentthat the weakened section balloons under pressure from the blood flowingthrough the artery. An aneurysm can lead to fatality if it rupturescausing rapid loss of blood.

An aortic aneurysm can be repaired by an endovascular repair procedure,in which a graft is inserted into the aneurysm via the femoral arteryeffectively to take the blood flow and to isolate the aneurysm. Thereare three forms of aortic endograft in current usage. The first is astraight stented tube graft. This may be used when there are adequateproximal and distal aortic necks for graft implantation. The tube may bestented at each end for support and to provide pins or hooks forembedding into the arterial wall to secure the tube in place.Alternatively, the tube may be stented throughout its length, such as bymeans of a metal wire stent. This form of endograft is used mostcommonly to repair aneurysms of the thoracic aorta.

An alternative construction of graft is a bifurcated tube for use in apatient with an abdominal aortic aneurysm where there is inadequatedistal aortic neck but appropriate iliac artery configurations.

The third variation of endovascular graft is an aortouniliac graft, inwhich the tube extends from the proximal aortic neck into one of theiliac arteries. With this configuration an extraanatomic femofemoralbypass graft with a contralateral occlusion device in the common iliacartery is required. This device may be used when significant aneurismaldisease is present in the contralateral iliac artery, precludingsuccessful bifurcated graft placement.

A problem with such grafts is that over time, even over a period of twoyears, the graft can slip due to wear and tear on the stents, the effectof pulsatile blood flow through the tube and changes in the morphologyof the arteries. The blood flow effect can be exaggerated as the graftslips and is able to bend and flex. Thus over time the integrity of thegraft and isolation of the aneurysm can be compromised.

Another problem with stented grafts is that the twisting or flexing ofthe graft can cause fatigue in the metal stent. Such fatigue leads tofracturing of the stent wire and the resultant wire ends can pierce thegraft material. Holes in the graft material mean that the aneurysm is nolonger isolated from the blood flow.

Such grafts are generally used in a planned manner with the graft beingselected for a specific patient according to precise pre-operativemeasurement of the aorta and adjacent arteries. Therefore, such graftsare not readily suited for use in repairing a ruptured aneurysm, wherean emergency procedure is required simply to prevent death.

SUMMARY OF THE INVENTION

An object of this invention is to provide a device for use in repairinganeurysms that does not suffer from the above-mentioned disadvantages.

According to this invention there is provided a device for repairing ananeurysm by deployment within the aneurysm, the device comprising agraft tube, at least part thereof having an inflatable wall, whereby thetube can be deployed in an artery and be inflated to contact at leastpart of the arterial wall.

The term arterial wall may include arterial wall that is undamagedand/or aneurysm wall.

Graft tubes of the invention may be made of any suitable biologicallycompatible material and especially of plastics material.

Graft devices of the invention may be straight tubes or bifurcated tubesfor use depending on the position and size of the aneurysm, i.e. fordeployment in a similar manner to conventional endograft graft tubes.The graft tube of this embodiment may be one that narrows from one endto the other for use in aortouniliac grafting. The device of theinvention may have an inflatable wall along its entire length or thedevice may have one or more discrete inflatable sections, especially atone or more ends of the tube.

Preferably the inflatable wall of the graft tube has an inner wall andan outer wall that is expandable in preference to the inner wall. Theinner wall may be reinforced compared to the outer wall. Reinforcementsof the inner wall may be, for example, by means of hoops, cages or mesh.Reinforcements may be of metal or plastics. Suitable metal reinforcementmaterials include stainless steel and nickel-titanium alloy. Suitableplastics reinforcement materials include inert polymers, such as, forexample, polytetrafluoroethylene. Alternatively, the inner wall may beof a different material to the outer wall or may be of the same materialbut of different thickness to achieve the desired effect of the outerwall expanding upon inflation in preference to the inner wall with theinner wall substantially retaining its shape. The inflatable wall of thetube is preferably inflated by insertion of a settable material.Preferably the material is introduced as a liquid and sets to a solid orsemi-solid state. The inflating material used will be biologicallycompatible and may, for example, be based on collagen or temperature/pHsensitive hydrogels, such as N-isopropyl acrylamide. It is possible thatfor stented graft tubes the inflating material need only set to apliable condition. However, if the graft tube of the invention is to bedeployed using a balloon to prevent an un-reinforced inner wallcollapsing while the inflatable wall is being inflated, the inflatingmaterial may need to set to a relatively rigid condition.

The tube may be deployed in an aneurysm by inflating the tube, so thatat least at the proximal artery position and ideally also at the distalartery position the tube grips the walls of the artery where there is nowall damage and between those positions the outer wall of the tubeexpands to contact the walls of the aneurysm and thereby support theaneurysm against flexing.

In one embodiment of the invention, a graft tube for use in repairingarterial aneurysms may have a first part with an inflatable wall to fitinto the neck of the artery above an aneurysm. The remainder of thegraft can be a straight, tapered or bifurcated tube.

Grafts of the invention may be deployed in an aortic aneurysm by meansof conventional endovascular techniques. Typically, a guide wire isinserted through the femoral artery to extend beyond the aneurysm andthe graft is guided into position along the wire. A narrow tube forinflating the twin walled part of the graft will be incorporated intothe graft, one end of which will be accessible for the purpose ofinjection within the access wound in the groin. Once inflated to adesired extent the inflation tube is sealed.

Additionally or alternatively, a graft according to the invention may bedeployed with the aid of an inflatable deployment balloon. Thus, a graftof the invention may be positioned in an aneurysm in collapsed formmounted on a deflated deployment balloon. The deployment balloon canthen be inflated to seal the graft to the arterial wall above and belowthe aneurysm before the outer part of the graft is inflated by means ofthe settable material to conform to the anatomy of the aneurysm.Finally, the deployment balloon is deflated and withdrawn.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention will now be further described, by way of example only,with reference to the accompanying drawings, in which:

FIG. 1 shows a first prior art aortic aneurysm repair technique;

FIG. 2 shows a second prior art aortic aneurysm repair technique;

FIG. 3 shows a third prior art aortic aneurysm repair technique;

FIG. 4 shows a first graft according to the invention;

FIG. 5 shows the graft of FIG. 4 in position in an aortic aneurysm;

FIG. 6 shows a second graft according to the invention in position in anaortic aneurysm;

FIG. 7 shows a third graft according to the invention in position in anaortic aneurysm;

FIG. 8 shows a first stage of deployment of a fourth graft according tothe invention;

FIG. 9 shows a second stage in the deployment of the fourth graftaccording to the invention;

FIG. 10 shows a third stage in the deployment of the fourth graftaccording to the invention; and

FIG. 11 shows a fourth stage in the deployment of the fourth graftaccording to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1 of the accompanying drawings, a tubular graft 10 isshown deployed in an aortic aneurysm 12. The aneurysm is situatedbetween proximal and distal regions 14,16 respectively of the aorta 18.This deployment is possible when there is adequate aortic tissue aboveand below the aneurysm for attachment of the graft. The graft is stented(20,22) at each end and has pins 24 extending from the stented regionsfor attachment to the aortic wall.

When there is inadequate aortic tissue below an aortic aneurysm forattachment of a graft as shown in FIG. 1 of the drawings, a bifurcatedgraft 30 can be used as shown in FIG. 2. Here the graft is attached inthe neck 32 of the aorta above the aneurysm 34 and the two tube 36resulting from the bifurcation are each deployed in an iliac artery 38below the aneurysm. Again the ends of the graft are stented (40) andpins 42 are provided to aid attachment to the artery walls.

If there is significant aneurismal disease in the contralateral iliacartery, which precludes use of a bifurcated graft of the type shown inFIG. 2, a graft 50 as shown in FIG. 3 may be used, which is deployedbetween the aorta 52 above the aneurysm 54 and the healthier iliacartery 56. The graft tube 50 narrows to compensate for the difference inwidths of the aorta and iliac artery. With this procedure anextraanatomic femofemoral bypass 58 is required with a contralateralocclusion device 60 in the common iliac artery 62. Again this graft 50is stented at both ends (64,66).

Turning now to FIGS. 4 and 5 of the accompanying drawings, there isshown a tubular endovascular graft 100 of the invention for use inrepairing an aortic aneurysm. The graft 100 is twin-walled having aninner wall 102 and an outer wall 104, whereby the space 105 between thewalls can be inflated by introduction of inflating material.

The outer wall 104 is relatively expandable compared to the inner wall102. Both walls may be of the same material but the inner wallreinforced, so that upon inflation, the outer wall expands to contactthe aneurysm wall, as shown in FIG. 5, whilst the inner wall 102 retainssubstantially its diameter, so as not to affect adversely blood flowthrough the graft. The inner wall 102 as shown is reinforced with metalhoops 106, although the reinforcement can be of other materials or takea different form. An alternative may be to make the inner and outerwalls of different materials to achieve a similar effect.

The graft 100 can be deployed in a similar manner to the graft shown inFIG. 1, i.e. between proximal and distal regions 110,112 respectively ofthe aorta 114 above and below the aneurysm 116. When in position thegraft is inflated by introduction of inflating material. This causes theouter wall of the graft to expand, firstly to grip the walls of theartery in those proximal and distal regions to fix the graft in placeand secondly to contact the walls of the aneurysm to provide supporttherefor and, in the case of rupture, to seal the leakage of blood bydirect closure of the tear in the aneurysm wall.

The inflating material is preferably a biocompatible material and may,for example, be based on collagen or temperature/pH sensitive hydrogels,such as N-isopropyl acrylamide. Preferably the inflating material is onethat can be introduced as a liquid but which sets to from a pliablemass, such as in the nature of a gel. Once sufficient inflating materialis introduced into the graft, possibly through a valve, the inflatedgraft is sealed.

In FIG. 6, a bifurcated graft 120 is shown which is similar in natureand general use to the graft 100 of FIGS. 4 and 5 but for the type ofsituation shown in FIG. 2 of the drawings, i.e. where there is aortictissue damage requiring iliac artery deployment.

In FIG. 7 of the accompanying drawings there is shown an alternativeform of inflatable tubular graft 150. The graft shown is a bifurcatedgraft but only a top portion 152 thereof is twin-walled. Thereby thegraft 150 can be deployed and the top portion 152 inflated as with otherembodiments of the invention to fix the graft in the proximal neck 154of the aorta 156 above the aneurysm 158. The iliac tubes 160,162 of thegraft may be fixed in the iliac arteries 164,166 in a conventionalmanner.

Turning to FIGS. 8 to 11 of the accompanying drawings, an endograft 200comprises an inner graft tube 202 and an outer inflatable balloon 204attached to the inner tube. The endograft shown is bifurcated but itcould also be a single stem straight or tapered endograft. The outerballoon is designed to be inflated to conform to the anatomy of ananeurysm.

The endograft 200 is delivered into aorta 206 in a collapsed statemounted over an inflatable deployment balloon 208. Once the endograft isin position, the deployment balloon is inflated to expand the graft toform seals at the anastomoses 210, 212 and 214 of the aorta and iliacarteries (see FIG. 9). With the deployment balloon 208 still inflated,the outer balloon 204 of the endograft is inflated with a substance thatrapidly sets to form a solid mass 216. Once that substance has set, thedeployment balloon is deflated and removed, leaving the endograftsupported by the inflated outer balloon that has conformed to thecontours of the aneurysm sac 218.

Fixation of the endograft can then be enhanced by placement of stents(with or without barbs or hooks), which secure the upper and lowerextremities of the graft to the surrounding arterial wall.

Advantages of grafts according to the invention include the possibilityof rapid deployment, which, in the case of a ruptured aneurysm is vital,because the graft does not have to be designed for a particular patient.The ability to inflate the graft to fix it in place means that the sametype of graft can be used in a variety of cases. The gel material usedto inflate the device, by filling the aneurysm sac, will stabilise theendograft and prevent buckling, migration and leaking over time. Theeffects of post-operative changes in the morphology of the aneurysm sacand adjacent blood vessels will also be minimised with improvedlong-term stability of the repair.

Another possible advantage of graft devices of the invention is thatthey can be deployed without the need for stents, which means that thestent fatigue problem can be avoided.

The endografts of the invention are primarily intended for plannedtreatment of aneurysms but may also be used for emergency sealing of aruptured aneurysm as a holding manoeuvre to stabilise a critically illpatient. Extensions and modifications may be made at a later date usingadditional inflatable or conventional endografts overlapping within thelumen of the first inflatable endograft using the “trombone” technique.

Inflated devices of the invention can seal aortic side branches andthereby completely isolate an aneurysm from systemic blood pressure.

1. A device for repairing an aneurysm by deployment within the aneurysm,the device comprising a graft tube, at least part thereof having aninflatable wall, whereby the tube can be deployed in an artery and beinflated to contact at least part of the arterial wall.
 2. A device asclaimed in claim 1 made of biologically compatible plastics material. 3.A device as claimed in claim 1 or 2, wherein the tube is a straight,tapered or bifurcated tube.
 4. A device as claimed in claim 1, 2 or 3,having an inflatable wall along its entire length.
 5. A device asclaimed in claim 1, 2 or 3, having one or more discrete inflatablesections.
 6. A device as claimed in any one of claims 1 to 5, whereinthe inflatable wall of the graft tube has an inner wall and an outerwall that is expandable in preference to the inner wall.
 7. A device asclaimed in claim 6, wherein the inner wall is reinforced compared to theouter wall.
 8. A device as claimed in claim 7, wherein reinforcement ofthe inner wall is by means of hoops, cages or mesh.
 9. A device asclaimed in claim 8, wherein reinforcement is of metal or plastics.
 10. Adevice as claimed in claim 9, wherein metal reinforcement is ofstainless steel or nickel-titanium alloy.
 11. A device as claimed inclaim 9, wherein plastics reinforcement is of polytetrafluoroethylene.12. A device as claimed in claim 7, wherein the inner wall is of adifferent material to the outer wall.
 13. A device as claimed in claim7, wherein the inner wall is of the same material as the outer wall butof different thickness.
 14. A device as claimed in any one of claims 1to 13, wherein the inflatable wall of the tube is inflatable byinsertion of a settable material.
 15. A device as claimed in claim 14,wherein the settable material is based on collagen or temperature/pHsensitive hydrogels.
 16. A device as claimed in claim 15, wherein thehydrogel is N-isopropyl acrylamide.
 17. A device as claimed in any oneof claims 1 to 16 including an inflatable deployment balloon within thegraft tube.
 18. A device for use in repairing aneurysms substantially ashereinbefore described with reference to and as illustrated in any ofFIGS. 4, 5, 6, 7, and 8 to 11 of the accompanying drawings.